Tuesday, 15 June 2010

To banish banding, just add noise....

Luckily I have never really encountered banding on a Tiff image which was output from Raw.

Until a few weeks ago when I shot this portrait on my Canon 5d MkII with a 'L' Series 35mm F1.4 Lens, which followers of this site will know I am a BIG fan of.

The ambient light was flooding in through a small one meter square window onto the sitter and the background.

With my photojournalist head on I knew if I shot at F1.4 it would give me a beautiful effect without using flash, I did after all cycle to the assignment, so I decided to go without any flash gear at all (shock horror!) when I'm in the mood it something I love to do

Banding, pretty uncommon for the most part but when it strikes it can be a real issue

I know of ad campaigns which have had very expensive reconstructive surgery in post production just to fix this issue

Banding is caused by the sensor failing to cope with a gradation in tones

Meaning it cannot record a sufficient range of tonality, so where it cannot record the shade of grey you get banding,

Now a Phase One camera shoots in 16 bit colour which is capable of recording a stunning 65,536 shades of grey but I shot the assignment on a Canon 5DMkII which shoots in 14 bit colour which is capable of recording 'only' 16,384 shades of grey but still so much better than the previous generation of DSLR's which shot in 8 bit colour which is only capable of recording a mere 256 shades of grey.

So what to do?

Here is the Images without my red scrawl all over it, complete with banding along with the default Capture One 5 settings

And here is the corrected image

And this is how I overcame the issue, by adding some fine grain noise to the image then 'softening' it using the Negative Clarity

Perhaps if I shot the image at a higher ISO I would not have encountered the issue but I wanted to shoot at 100 ISO to give a creamy smooth look

Drew, thanks for the knowledge sharing. My banding problems have always been at the output to print. I'm now wondering if this wasn't always in the image and exaggerated in the final print, I just wasn't keen to see it before. I'll be reviewing some images to find out.